Internal combustion engines require a source of combustion air. A typical source for combustion air is air drawn from outside of the vehicle, which commonly includes particulate contaminants. An air cleaner including an air filter element is normally provided in the air induction system to capture these particulate contaminants before combustion air is delivered to the vehicle engine. When operated in colder climates where heavy or blowing snow is common, snow may be drawn into the air cleaner and lead to eventual blockage of the air filter element, thereby cutting off the supply of combustion air and leading to poor engine performance.
In the prior art, air cleaners are known that include a secondary air inlet having a movable damper or power operated valve operable to open a secondary air supply to the air cleaner when the primary air supply becomes obstructed by snow. One example is U.S. Pat. No. 4,969,939, which discloses an air cleaner, equipped with a slideable valve including mechanical linkage extending into the operator cabin and operable by a vehicle operator to admit secondary air into the air cleaner in the event the normal air inlet becomes blocked by snow.
U.S. Pat. No. 6,395,048 discloses an air cleaner having an annular door with an open window that is rotatable between a first and a second position. In the first position outside air is admitted to the air cleaner. In the second position warmer under the hood air is provided to the air cleaner and the normal outside air inlet is blocked. A mechanical actuator rotates the door.
As can be understood from the above, many varieties of air cleaners equipped for secondary air induction are known. As can be seen from the prior art, air cleaners equipped for secondary air induction have a number of moving parts, are more complex and are therefore more costly that similar air cleaners lacking secondary air adaptations.